The relationship between the pair has remained acrimonious for several years with bitter words exchanged since Keane left the club in November 2004.
Having played for 13 years under Sir Alex at Old Trafford, the 1999 treble-winner's relationship with United began to unravel after his well-documented criticism of team-mates on a MUTV programme that was pulled from the schedules due to its content.
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And the 48-year-old still holds a resentment for his former manager, who he believes depicted him as a disruptive influence in the dressing-room during his final months in Manchester.

Roy Keane has reignited his war of words with former boss Sir Alex Ferguson

Image credit: Getty Images

"I wouldn't forgive Ferguson. The media spin, how I apparently upset everybody, it was all nonsense," he told Off the Ball.
"I don’t care if it’s Alex Ferguson or the Pope, you’re going to defend yourself.
I think when he apologises I will probably say hello to him, yeah. [But] I've no interest in speaking to the man.
"People talk about Ferguson’s man-management. Don't be kidded by all that.
"I was at the club when Bryan Robson left, when Steve Bruce left, two brilliant servants for Manchester United, and I didn't like the way they were treated."

Steve Bruce and Bryan Robson celebrate winning the Premier League title in 1994 (PA)

Image credit: PA Photos

Robson won the Premier League with United in 1993 and 1994 - the same year in which he was left out of the FA Cup final squad and saw Eric Cantona handed his No 7 shirt.
Ferguson had blocked Bruce from pursuing a career in management in the summer of 1995, on the grounds that he remained a key part of his squad, but the former centre-back was subsequently left out of ther 1996 FA Cup final.
Keane was most recently assistant manager at Nottingham Forest, but he left that post in June.
Now in full flow, the former Republic of Ireland midfielder also accused Ferguson of nepotism, with his son Darren part of the 1992/93 Premier League winning squad.
Keane, who scored 51 goals in 480 appearances for United, added: "Darren Ferguson [his son] won a medal. He was very lucky.

Keane challenges Darren Ferguson during his Nottingham Forest days

Image credit: Getty Images

"His brother was the chief scout for Manchester United for a long time. I'm surprised his wife wasn't involved in the staff somewhere.
"Darren was [the manager] at Preston North End and lost his job. He had a couple of young players on loan from Manchester United. Guess what happens the next day?
"They're pulled out of Preston. Is that doing the best for Manchester United? Do me a favour."
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